This invention relates to a transformer, comprising, a primary winding and a secondary winding, the primary winding comprising at least one first primary coil which is wound in the form of a solenoid and an end of which is conductively connected to a primary reference point, the secondary winding comprising at least one secondary coil which is wound in the form of a solenoid and an end of which is conductively connected to a secondary reference point, which coils are concentrically arranged on a coil former with intermediate electrical insulating means.
A transformer of this kind is known, for example, from U.S. Pat. No. 4,089,049. It is described therein that a disturbing voltage occurs between the primary and the secondary reference point of such a transformer. This disturbing voltage is caused by the voltage across the windings and the parasitic capacitance between the windings. In the known transformer the disturbing voltage is suppressed by mounting electrostatic shields between the primary and secondary windings. This method provides the desired result, but also has a number of drawbacks. The mounting of the shields increases the dimensions and the weight of the transformer and reduces the coupling factor between the windings. Eddy currents are liable to occur in the shields, so that the transformer losses increase. The presence of the shields makes it difficult to satisfy some severe requirements imposed as regards the electrical insulation between the primary and secondary sides of the transformer.